Hazards Halt Manhattan Bridge Subway Line

By DENNIS HEVESI

Published: December 28, 1990

New York City transportation officials shut down a subway line across the Manhattan Bridge yesterday after state inspectors found deep corrosion, sheared bolts and missing steel plates in the bridge's beams that support the tracks.

In one spot, a plate that was supposed to hold a six-inch-wide beam in place was missing, said David Steinberger, the city's Deputy Transportation Commissioner for bridges.

With the plate missing, the beam had slipped to within a half inch of falling off its support, Mr. Steinberger said. That might have dropped the track a foot or more and caused a train to derail. Thousands Inconvenienced

Two tracks were closed along the south side of the bridge, a suspension bridge that is 81 years old and stretches 2,195 feet across the East River. The closings affected about 25,000 passengers who use the N trains. The trains were rerouted through the Montague Street tunnel south of the bridge, adding about 10 minutes to the trip across the river.

But more serious delays are likely to arise this weekend, when the other subway tracks on the bridge -- the B, D and Q lines along its north side -- are also closed for inspections that had already been scheduled by the State Department of Transportation. The supports under the B, D and Q lines are distinct from those of the N line and were recently strengthened, city officials said.

Repairs on the N tracks are expected to take about a week, city officials said. Repairs Cost Money

The new problems on the Manhattan Bridge illustrate the difficulties New York City faces as the need to repair many of its 842 bridges collides with the city's severe budget constraints. The number of hazardous conditions on the bridges, which have been poorly maintained for decades, has risen so sharply in recent months that city engineers have warned that dozens of bridges might have to be temporarily closed next year for repairs.

"Any time you have to shut down a roadway or a trainway it's serious," the city's Transportation Commissioner, Lucius J. Riccio, said yesterday. "This is kind of heart-breaking to me because it's a disruption of train service. And with all the roads and bridges we're working on, the city needs all its train service."

The N line on the bridge had been closed for two years because of structural problems with the bridge, but the line was reopened in September without major repairs having been made. Asked yesterday whether reopening those tracks had been a mistake, Mr. Riccio said: "No. I think we've been providing good service for the people of Brooklyn who use that train.

"The major contract for the repairs hasn't worked out," he continued, "but we did a lot of emergency work to get it in shape. That bridge is so problematic, however, that we knew there was the possibility that trains would have to be taken off on an intermittent basis."

Because of the city's fiscal problems, transportation officials plan to reduce the preventive-maintenance program for bridges by 38 percent in 1991, to $5.8 million from $9.4 million. They also plan to cut the capital budget by 16 percent over the next four years, to $817 million from $972 million. The Transportation Department has said that the cuts will delay 19 bridge rehabilitation projects and cancel plans to clean 310 bridges and paint 1.6 million square feet of them. 400 Bridges Behind Schedule

"The bridge problem is not going to go away in a year," Mr. Riccio said. "We have a minimum of 10 years of rebuilding ahead of us to dig out of the four- or five-decade hole we inherited. We should open up 20 to 30 rehabilitated bridges this year. The problem is we've got a backlog of 400 bridges that need to be rehabilitated."

Mr. Steinberger said the new problems on the Manhattan Bridge bring the number of red flag conditions on it to more than 300. A red flag is defined as an imminent or actual structural failure that could lead to collapse. There are more than 1,000 red or yellow flag conditions on the city's bridges, Mr. Steinberger said. A yellow flag indicates a potential hazard.

"What we have seen over the last year," Mr. Steinberger said, "is that even though we have doubled the rate at which we repair flag conditions -- that's from 50 a month to 100 per month -- we're still identifying flag conditions faster than we can repair them."

The first of the new problems on the Manhattan Bridge was discovered on Wednesday evening by engineering consultants hired by the state, said Phyllis Hirschberg, assistant to Michael Francese, the New York City regional director for the state Transportation Department. 'Serious Deterioration'

"They found a red flag on a stringer -- that's a 12-foot-long steel support beam -- underneath the tracks that the N train runs on, which is on the south side of the bridge," Ms. Hirschberg said. "There was serious deterioration." City officials then decided to close that Brooklyn-bound track immediately.

Yesterday morning, she said, similar conditions were found below the Manhattan-bound track. That track was closed about 11:30 A.M.